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JEE Main 2026 (Online) 21st January Morning ShiftMCQEasy📈 Topic in 5% papers+4−1
Ques. 1JEE Main 2026, 21 January (Morning Shift)

If an alpha particle with energy 7.7 MeV is bombarded on a thin gold foil, the closest distance from nucleus it can reach is m. (Atomic number of gold = 79 and 14 0 = 9 109 in SI units)

  1. 2.95 10-16
  2. 3.85 10-14
  3. 2.95 10-14
  4. 3.85 10-16

Answer

(3) 2.95 10-14

Solution

At the distance of closest approach r0, the whole kinetic energy changes into electrostatic potential energy:

K = 14 0 (2e)(Ze)r0

r0 = 14 0 2Ze2K, with K = 7.7 106 1.6 10-19 J

r0 = 9 109 2 79 (1.6 10-19)27.7 106 1.6 10-19

r0 = 9 109 158 1.6 10-197.7 106

r0 2.95 10-14 m

Answer: (3)

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Ques. 2JEE Main 2026, 21 January (Evening Shift)

The energy of an electron in an orbit of the Bohr's atom is -0.04E0 eV where E0 is the ground state energy. If L is the angular momentum of the electron in this orbit and h is the Planck's constant, then 2 Lh is :

  1. 6
  2. 2
  3. 5
  4. 4
Ques. 3JEE Main 2025, 7 April (Morning Shift)

In a hydrogen like ion, the energy difference between the 2nd excitation energy state and ground is 108.8 eV. The atomic number of the ion is:

  1. 1
  2. 4
  3. 3
  4. 2
Ques. 4JEE Main 2025, 7 April (Morning Shift)

For a hydrogen atom, the ratio of the largest wavelength of Lyman series to that of the Balmer series is

  1. 5 : 27
  2. 27 : 5
  3. 3 : 4
  4. 5 : 36
Ques. 5JEE Main 2025, 4 April (Morning Shift)

Considering the Bohr model of hydrogen-like atoms, the ratio of the radius of 5th orbit of the electron in Li2+ and He+ is

  1. 32
  2. 23
  3. 49
  4. 94
Ques. 6JEE Main 2025, 4 April (Evening Shift)

Given below are two statements : In the light of the above statements, choose the most appropriate answer from the options given below :

  1. Both Statement I and Statement II are correct
  2. Statement I is correct but Statement II is incorrect
  3. Both Statement I and Statement II are incorrect
  4. Statement I is incorrect but Statement II is correct
Ques. 7JEE Main 2025, 3 April (Evening Shift)

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. In the light of the above statements, choose the correct answer from the options given below

  1. A is true but R is false
  2. Both A and R are true and R is the correct explanation of A
  3. A is false but R is true
  4. Both A and R are true but R is NOT the correct explanation of A
Ques. 8JEE Main 2025, 3 April (Evening Shift)

An electron in the hydrogen atom initially in the fourth excited state makes a transition to nth energy state by emitting a photon of energy 2.86 eV. The integer value of n will be .

Ques. 9JEE Main 2025, 2 April (Morning Shift)

Considering Bohr's atomic model for hydrogen atom : Choose the correct answer from the options given below :

  1. (A), (B) only
  2. (A), (D) only
  3. (A), (C) only
  4. (B), (D) only
Ques. 10JEE Main 2025, 2 April (Evening Shift)

Assuming the validity of Bohr's atomic model for hydrogen-like ions the radius of Li++ ion in its ground state is given by 1Xa0, where X = (Where a0 is the first Bohr's radius.)

  1. 2
  2. 9
  3. 1
  4. 3
Ques. 11JEE Main 2025, 29 January (Evening Shift)

The number of spectral lines emitted by atomic hydrogen that is in the 4th energy level, is

  1. 3
  2. 6
  3. 1
  4. 0

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